Modern industry has a need for higher steam temperatures than conventional steam heaters can deliver. This need has led to the development of steam superheaters which are adapted for use with conventional steam systems and which are designed to raise the temperature of the steam to approximately 750.degree. F.
Prior art superheaters raise the temperature of the steam by exposing a coil containing the steam to exhaust gases from a furnace, thus heating the steam principally through convection. This method is singularly wasteful as it dissipates the radiant heat produced by said furnace in conventional furnace refactories. A problem is also caused by the great heat buildup along the coil system surfaces, which if not reduced to a tolerable level, results in rapid deterioration and rupture of said coil system.
This invention utilizes both radiant heat absorption and heat absorption by convection. The radiant heat energy is absorbed by the inner surface of said coil system, and heat remaining in the exhaust gases is further absorbed by convection by the outer surface of said coil system forming the outer exhaust passage. The heat buildup is reduced by using a very high steam velocity, between 5000 and 9000 feet per minute, to conduct the heat very rapidly from the surfaces of said coil system, thus enabling the coil system to be constructed of thinner walled material than prior art superheaters.
It is an object of this invention to provide a superheater for steam which absorbs heat energy both by radiation and convection.
It is a further object of this invention to provide a thin walled highly efficient steam heating coil system in which heat buildup is dissipated by introducing steam into said coil system at very high velocities, thus rapidly scrubbing the buildup heat away from the surfaces of said coil system and providing controls for limiting the temperature within the coil material to permit a relatively inexpensive but safe superheater to be produced.